7-Synatic Transmission 1 Figs BW

In the case of peptide neurotransmitter they are made

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Unformatted text preview: e case of peptide neurotransmitter, they are made of cell body and transported through axon to presynaptic terminal. 2. storage of neurotransmitter: this is done in vesicles. neurotransmitter are concentrated within the vesicles in high concentration, this action require specific transporter molecules, seen as green dot. the transporter molecules are responsible for uptake of specific neurotransmitter from the presynaptic cytoplasm into vesicle, this is a form of active transport. 3. release of neurontransmitter: this occur when action potential conduct itself way to the axon, arrive at the terminal. Presynaptic Terminal 2 T 3 Postsynaptic Terminal 4 T Receptor 1 P 5 T enzyme T re-uptake diffusion 1. Synthesis 2. Storage 3. Release 4. Receptor Interaction (ionotropic or metabotropic) 5. Inactivation Neurotransmitter Release 1. see action potential at top. ap conduct down the axon into the terminal. the currents are spreading down the axon and out across the presynaptic membrane. when current spread out, it depolarizes the presynaptic membrane. this is event 1: voltage-gated sodium+potassium channels are responsible for active conduction of active potential down the axon. In some presynaptic terminal there are also voltage-gated sodium/potassium channels, so AP actively invade the terminal. in some other presynaptic, there are no active propagation of signal into the terminal, but passive conduction would suffice (?) 2. event 2 is caused by presence in pre-synaptic terminal, at transmitter release side voltage-gated calcium channel. at normal membrane potential, resting terminal are close. with depolarization by AP, voltage-gated channel open, calcium enter the cell through steep electrochemical gradient, and there's a great localize increase in intracellular calcium right at release sites. 3. vesicle collapse and retrieval step 3, this localize increase of calcium ions near release sites trigger the exocytosis of neurotransmitters by pre-formed synaptic vesicles. exocytosis is seen at...
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